Transistor unit



G. C. RICH TRANSISTOR UNIT Dec. 7, 1954 Filed June 5, 1955 I BY Z2161 Ip 2,696,574 E'Patentecl Dec. 7, 1954 TRANSISTOR UNIT Gerald C. Rich,Scottsdale, Ariz., assignor to Motorola Inc., Chicago, Ill., acorporation of Illinois Application June 5, 1953, Serial No. 359,909

5 Claims. (Cl. 317235) The present invention relates to semi-conductortransistor units and more particularly to an improved and simplifiedtransistor unit of the point contact type.

The point contact type of transistor usually comprises a crystal ofsemi-conductive material, such as germanium or silicon, that has beentreated with impurities of the donor or acceptor types to form an N or Ptype semi-conductor.

The point contact type of transistor usually includes a pair ofelectrodes known respectively as emitterand collector which extendperpendicularly to a surface of the crystal and having pointedextremities in contact with that surface. A third electrode, which isusually in the form of a metal block or tab, is also provided andaflixed to another surface of the crystal to constitute a base electrodefor the unit.

The emitter and collector electrodes of prior art transistor unitsusually take the form of a pair of pointed fine wires or thin metallicribbons supported to extend in spaced parallel relation perpendicular toone face of the crystal. These electrodes usually have a diameter of theorder of .002" with a spacing between their points of .002". Moreover,the crystal is usually a cube with a .032" side. Therefore, thetransistor unit is an extremely small device and the fine wire emitterand collector electrodes are of microscopic dimensions and spacing. Thisspacing of such electrodes, it is difiicult, if not impossible,

to achieve any degree of uniformity between individual ones of aplurality of transistor units constructed in this manner. Moreover, theuse of fine wires for the collector and emitter electrodes in pointcontact transistor units usually results in a device that is extremelydelicate and which has a relatively low mechanical stability.

It is an object of the present invention to provide an improved pointcontact transistor unit that may be manufactured easily and with aminimum of mechanical skill, and which is so constructed that uniformcharacteristics may be attained between individual ones of a quantity oftransistor units manufactured in accordance with the invention.

Another object of the invention is to provide such an improved pointcontact transistor unit that is rugged in its construction and whichpossesses a high degree of mechanical stability.

A feature of the invention is the provision of a pair of resilientmetallic strips supported in a unique manner on an insulating base andhaving bent-over ends which extend parallel to one another with edges attheir extremities constituting the emitter and collector electrodes forthe unit. A semi-conductive crystal is resiliently supported against thebent-over ends by a base electrode with an edge of the crystaltraversing the edges of the bent-over ends and in electrical contacttherewith.

Another feature of the invention is the provision of such an improvedtransistor unit in which the edges of the bent-over ends of theresilient metallic strips mentioned above are each sharpened to a knifeedge and are inclined in opposite directions, the crystal beingresiliently supported by the base electrode so that an edge thereofcontacts the knife edges of the bent-over ends at the apex formedthereby. This construction allows the crystal to be resilientlysupported and accurately positioned against the knife edges, andeliminates any tendency for the crystal to shift laterally along theknife edges.

Yet another feature of the invention is the provision of a thin sheet ofinsulating material interposed between the bent-over ends of theresilient metallic strips to insulate and separate these ends andeliminate the need for accuratemicroscopic spacing between the endsduring the fabrication of the unit.

The above and other features of the invention which are believed to benew are set forth with particularity in the appended claims. Theinvention itself, however, together with further objects and advantagesthereof, may best be understood by reference to the followingdescription when taken in conjunction with the accompanying drawing inwhich the single figure shows a preferred embodiment of the invention.

The transistor unit of the present invention comprises a flat insulatingbase with a pair of rigid spaced parallel metallic leads extendingperpendicularly through the base at the respective ends thereof. A pairof resilient metal lic strips are secured respectively at one end to theleads and extend toward one another in a plane essentially perpendicularto the plane of the base. The metallic strips each have a turned-up end,and these turned-up ends are in spaced parallel relation and haverespective edges at the extremities thereof. A third rigid metallic leadextends through the base perpendicularly thereto and intermediate thefirst mentioned pair of leads. A semiconductive crystal is providedwhich has a pair of inclined faces having an edge formed by the line ofjuncture between such faces. Finally, a resilient metallic strip issecured to the third metallic lead at one end and has its other endsoldered to another face of the crystal. The last mentioned end of themetallic strip constitutes a base electrode for the crystal, and themetallic strip supports the crystal against the turned-up ends of thepair of strips with the edge of the crystal contacting the edges of theturned-up ends in transverse relation thereto.

The transistor unit of the invention includes a flat insulating base 10having a pair of rigid metallic leads 11 and 12 extendingperpendicularly therethrough at opposite ends thereof. A pair ofresilient metallic strips 13, 14 composed, for example, of Phosphorbronze are respectively Welded at one end to leads 11 and 12. Themetallic strips 13 and 14 extend inwardly from leads 11 and 12in a planeessentially perpendicular to the plane of insulating base 10 and have apair of bent-over ends 13:: and 14a which extend parallel to oneanother. The ends 13a and 14a have respective edges 13b and 14b whichare sharpened to a knife edge and which are oppositely inclined to forman apex therebetween.

The bent-over ends 13a and 14a are separated and insulated by a sheet orfilm 15 of insulating material which is interposed between these endsand which, for example, may have a thickness of 1 mil. Insulatingmaterial 15 can be composed, for example, of a material marketed underthe trade-mark of Teflon.

A third rigid metallic lead 16 extends perpendicularly through base 10intermediate leads 11 and 12 and has an S shape. A resilient metallicstrip 17, which also may be composed of Phosphor bronze, is welded tothe upper side of lead 16 and has a bent-over end 18 whichis soldered toa parallelopiped semi-conductive crystal block 19, the end 18 of strip17 forming a base electrode for the crystal. Crystal 19 has a pair ofinclined faces 20, 21 with the line of juncture therebetween forming anedge of the crystal. Resilient strip 17 supports the crystal with itsedges transversing the edges 13b and 14b of bent-over ends 13a and 14ain electrical contact therewith.

With the construction described above, the end 18 of strip 17 forms abase electrode for the crystal 19 and electrical connection is made tothe base through lead 16 andstrip 17. The edges 13b and 14b of thebent-over end of strips 13 and 14 constitute respectively the emitterand collector electrodes for the crystal and each make a point contactwith the edge of the crystal at spaced points along that edge.Electrical connection is made to the emitter electrode through lead 11and portion 13; whereas electrical connection may be made .to thecollector electrode through lead 12 and portion 14.

edges 13b and 14?).

The crystal is resiliently suspended, by the construgtion describedabove, between base electrode 18 and knife edges 13b and 14b, and isheld firmly against lateral shifting along the knife edges due to theinclined configuration of these edges.

The improved transistor unit of the present invention may be constructedin a relatively simple manner and no accurate and delicate spacing ofthe various electrodes thereof is required during the 'manufacturingprocess. In the construction of the unit,'strip 13 may first be weldedto lead '11 and film 15 adhered to the bent-over portion of that strip.The bent-over portion 14a of strip 14is then brought against the otherface of the insulating film and strip 14 is welded to lead 12.Alternately, the unit may be assembled with the bent-over portions incontactjwith one another and the insulating film then slippedbetween'them. The metallic strip 17 may then be Welded to lead 14 andsoldered to the crystal, the edge of the'crystal being-accuratelybrought to the de sired point ofcontact between'it "and the edges 13!)and 14b by'the inclined configuration of these edges.

The resulting assembly is relatively rugged since, inls'tead of fine anddelicate vi/ireelectrodes, the electrodes .are formed by metallic stripswhich are'supported in an improved manner to maintain the crystal inproperposition'therebetween. Moreover, there is no need forminutespacin'g adjustments during the manufacturing process sincetheemitter and collector electrodes are ac- ,cur'atelyspacea andinsulated by the film 15. In addition, there is no requirement formanual locating of these electrodeson the crystal edge, since the properloeationis obtained automatically due to the inclination of With'thisconstruction the units may be assembled rapidly and with a minimum ofre- "jects, and individual units of a plur'ality'so assembled exhibituniform characteristics since 'a standardized spacing "andlocat'ion ofthe electrodes may be achieved.

' While a particularembodiment of the invention has beenshown anddescribed, modifications may be made and itis intended in the appendedclaimsto cover all such'modificatio'ns as fall'within the true spiritand scope of the invention.

I'claim:

1. A circuit element including in combination, a fiat insulating-base,apair of rigid spaced parallel metallic leads extending perpendicularlythrough said base, a

pair of resilient'metallicstrips respectively secured to said leads'andextending toward one another in a plane essentially perpendicular'tothe plane of said base, said metallic stripseach having a turned-up end,and the turned-up ends of said strips being in spaced parallelrelationfa'nd "having respective edges at the extremities thereof, athird rigid metallic lead extending throu'ghsaid base, a'semi-conductive'devicehaving a pair of inclined faces with,an edge formed bythel'ineLOfjuncture between saidfaces, and a resilientmetallicfstrip's'ecured to said third metallic lead, and tosaidse'mi-conductivedevice for'supporting'said device aga'instfsaid,turned-up ends of said metallic strips'w'ithsaid edge of saiddevicec'ontacting said edges of said turned-up ends in transverserelation thereto. 7

2. A cireuitelementincluding in combination, a base portion, apairofrigid-electrically conductive supporting j'leads extending,th'roughfs'aidbase and spacedone from the other, 'a pair of resilientelectrically conductive "supporting members respectively secured to:said leads and extend 'tbw rdnn nqther sa d e ilie mb eachhavingaturned-upend, and the turned-upends of said resilient r'nembersbeing in spaced parallel relation and' having respectivefedg'es at theextremities thereof, a :third rigid electrically co'nductive supportinglead extending throughfsaid base,-a semi-conductiveidevice having'a'pair of inclined faces with an *edge' formed b'y ,the line ofjuncture between said faces, and a resilienfielec- 'trically' conductivemember secured to said third lead and to said semi-conductive devicefor'su'ppor'ting' said device "againsr' aiq lt ur'ried upfends' ofsaidfirst mentioned resilient supporting members 'with"said edge ofsaid-devicecontac'tiiig 'said edgesef s'aid turned-up ends in transverserelation thereto.

Number 3 A circuit element including in combination, a fiat insulating"base, a pair "of spaced "partner ri'g'id 'inetanie leads extendingperpendicularly through said base at the respective ends thereof, a pairof resilient metallic strips each having one end secured to and inelectrical contact with a respective one of said leads, said stripsextending toward one another in a planeessentially perpendicular to theplane of said base and having ninety degree bentover parallel adjacentends, said bent-over ends forming electrodes and having oppositelyinclined knife edges at the extremities. thereof forming an apextherebetween, a sheet of insulating'materialinterposed'between saidbentover ends to separate and insulate said bent-over ends from oneanother, a third rigid metallic lead extending through saidba'seintermediate said pair of leads, a semiconductive crystal havinga'pair of inclined faces with an edge formed by the line of juncturebetween said faces, and a resilient metallic strip secured to said thirdmetallic lead at one end-and secured to another face of said crystal atits other end, said last mentionedend forming an electrode for 'saidcrystal and said last mentioned strip supporting said crystal againstsaid bentover ends of said pair of metallic strips with said edge ofsaid crystal contacting said'knife edges of said 'bentover ends intransverse relation thereto at the apex formed thereby.

4. A circuit element including in combination, aflat insulating base,'apair of spaced parallel rigid metallic 'leads extending perpendicularlythrough 'said base, a pair of resilient metallic strips respectivelysecured to said leads and extending toward one another in a planeessentially perpendicular to the plane of said base, said metallicstrips each having a turned-up end, and the turnedup ends of said stripsbeing parallelon'e to the other and havingrespective oppositely inclinedknife edges at the extremities'thereof forming an apex therebetween, asheet of insulating material interposed between said turnedup ends toseparate and insulate said turned-up ends from one another, a thirdrigid metallic lead extending through said base, a semi-conductivedevice having "a pair of inclined faces with an edge formed by the lineof-junctu're betwee'nsaid faces, and a resilient metallic strip securedto said third metallic lead and to said semiconductive'device forsupporting said'device against said turned-up ends'of said pai'r ofmetallicstrips with said I towardbne another in a plane essentiallyperpendicular to the plane of said'base and having'turned-upends inmutually spaced parallel relation, said turned-up ends formingelectrodes and having respective knife edges at the extremities thereof,a third rigid metallic leadextending through -said base, asemi-conductive crystal having a pair of inclined faces with anedgeformed'by theline of juncture between said faces, and a resilientmetallic strip secured to said third metallic lead atone end and secured.to' a further face of said semi-conductive crystal at'its other-end,said last-mentioned end forming an eleetrodefor said semi-conductivecrystal, and said last mentioned strip supporting saidicry'stal againstsaid turned-upends'of saidpair'of metallicstrips with said edge ofsaid'crystal contacting said 'knife edges'of said turned-up ends'intransverse relation thereto.

References Citedin the file of this patent UNITED, STATES PATENTS NameDate 2,609,427 -St'elmak Sept. 2, '1952 2,641,639 Slade June-9, 19532,671,189 Gaudlitz'u- Mar. 2, 1954

